xt_quota.c revision bd414ee605ff3ac5fcd79f57269a897879ee4cde 
1/*
2 * netfilter module to enforce network quotas
3 *
4 * Sam Johnston <samj@samj.net>
5 */
6#include <linux/skbuff.h>
7#include <linux/spinlock.h>
8
9#include <linux/netfilter/x_tables.h>
10#include <linux/netfilter/xt_quota.h>
11
12struct xt_quota_priv {
13	uint64_t quota;
14};
15
16MODULE_LICENSE("GPL");
17MODULE_AUTHOR("Sam Johnston <samj@samj.net>");
18MODULE_DESCRIPTION("Xtables: countdown quota match");
19MODULE_ALIAS("ipt_quota");
20MODULE_ALIAS("ip6t_quota");
21
22static DEFINE_SPINLOCK(quota_lock);
23
24static bool
25quota_mt(const struct sk_buff *skb, const struct xt_match_param *par)
26{
27	struct xt_quota_info *q = (void *)par->matchinfo;
28	struct xt_quota_priv *priv = q->master;
29	bool ret = q->flags & XT_QUOTA_INVERT;
30
31	spin_lock_bh(&quota_lock);
32	if (priv->quota >= skb->len) {
33		priv->quota -= skb->len;
34		ret = !ret;
35	} else {
36		/* we do not allow even small packets from now on */
37		priv->quota = 0;
38	}
39	/* Copy quota back to matchinfo so that iptables can display it */
40	q->quota = priv->quota;
41	spin_unlock_bh(&quota_lock);
42
43	return ret;
44}
45
46static int quota_mt_check(const struct xt_mtchk_param *par)
47{
48	struct xt_quota_info *q = par->matchinfo;
49
50	if (q->flags & ~XT_QUOTA_MASK)
51		return -EINVAL;
52
53	q->master = kmalloc(sizeof(*q->master), GFP_KERNEL);
54	if (q->master == NULL)
55		return -EINVAL;
56
57	q->master->quota = q->quota;
58	return 0;
59}
60
61static void quota_mt_destroy(const struct xt_mtdtor_param *par)
62{
63	const struct xt_quota_info *q = par->matchinfo;
64
65	kfree(q->master);
66}
67
68static struct xt_match quota_mt_reg __read_mostly = {
69	.name       = "quota",
70	.revision   = 0,
71	.family     = NFPROTO_UNSPEC,
72	.match      = quota_mt,
73	.checkentry = quota_mt_check,
74	.destroy    = quota_mt_destroy,
75	.matchsize  = sizeof(struct xt_quota_info),
76	.me         = THIS_MODULE,
77};
78
79static int __init quota_mt_init(void)
80{
81	return xt_register_match(&quota_mt_reg);
82}
83
84static void __exit quota_mt_exit(void)
85{
86	xt_unregister_match(&quota_mt_reg);
87}
88
89module_init(quota_mt_init);
90module_exit(quota_mt_exit);
91